In offshore drilling and production, there is often a need to provide piping extending from the sea floor to the surface where the drilling or production platform is positioned. This piping can act as a tension leg for supporting the platform, a conduit for drilling or production, a conduit for providing pressurized fluids for control functions to a sea floor unit from the platform, or any combination of these functions.
A critical consideration in such pipe construction is the movement of the platform relative to the sea floor. In the past, expensive flexible pipes have been rigidly mounted at the sea floor to extend to the platform to accommodate this motion. If a fluid passage is necessary in such a pipe, in the past, concentric flexible pipes have been employed. However, as these flexible pipes move, the annular area between the pipes defining the passage varies in cross-sectional area.
A need exists for an improved technique for connecting sea floor equipment with a surface platform while providing for one or more passages through the pipe for communication between the platform and sea floor equipment.